“Did Rome know they were forgeries?”
Do you have even a single shred of evidence that they did know the Donation of Constantine was a forgery when the document first showed up? I doubt you do, because no historian has ever found any.
“Deception or ignorance?”
Ignorance. As is clear with the Donation of Constantine, the papal court did not know it was a forgery in the decades and even first centuries after it appeared. Then, because of its great age, it was assumed to be genuine.
Not so fast...from http://beggarsallreformation.blogspot.com/search?q=donation+of+constantine, we learn:
In the eighth century, Constantine was known primarily through the account of him in the legend of Pope Sylvester. In this he was incorrectly portrayed as an emperor who had persecuted Christianity until struck down with leprosy. On rejecting the suggestion of his pagan priests that he bathe in the blood of sacrificed babies, he had a vision of Saints Peter and Paul telling him to find Bishop Sylvester, who cured, healed and baptized him. Onto this core narrative was grafted the claim that when Constantine subsequently decided to leave for the East, out of gratitude he entrusted Pope Sylvester with a set of imperial regalia, including a crown, and with the authority for himself and his successors to appoint an emperor in the West should circumstances ever require it. (Roger Collins, “Keepers of the Keys of Heaven,” New York: Basic Books (2009) 148-149)
Derek Wilson, in his biography of Charlemagne, is a bit more descriptive:
We decree that the sacred See of Blessed Peter shall be gloriously exalted even above our Empire and earthly throne … as over all churches of God in all the world … We convey to Sylvester, universal Pope, both our palace and likewise all provinces and palaces and districts of the city of Rome and Italy and of the regions of the west.
In other words, papal territory had for centuries been an independent state and had ever been part of the [French] exarchate. The so-called Donation of Constantine was a thoroughgoing forgery, made for a specific purpose, at a particular place and time. It was the means chosen to achieve a specific end in a desperate situation, and it doubtless did not occur to the criminals who created it that it would be used to excuse a millennium of political intrigue, wars and carnage. (Derek Wilson, “Charlemagne” New York: Doubleday (2006) 23-24).
The document itself, a complete fabrication, was used to twist the arms of kings in that day and for many centuries beyond. It set up the tensions -- an untenable situation, really, that made the “break” of the Reformation so much more dramatic.
As the Catholic Encyclopedia notes, “Gregory VII himself never quoted this document in his long warfare for ecclesiastical liberty against the secular power. But Urban II made use of it in 1091 to support his claims on the island of Corsica. Later popes (Innocent III, Gregory IX, Innocent IV) took its authority for granted (Innocent III, Sermo de sancto Silvestro, in P.L., CCXVII, 481 sqq.; Raynaldus, Annales, ad an. 1236, n. 24; Potthast, Regesta, no. 11,848), and ecclesiastical writers often adduced its evidence in favour of the papacy.” We can see some of the further “fruit” of that document also in, for example, the Papal Bull Unam Sanctam, in which another pope is still emphasizing his superiority over another French king. (In this document, Boniface VIII proclaims that “we declare, we proclaim, we define that it is absolutely necessary for salvation that every human creature be subject to the Roman Pontiff.”)
In fact, the legend behind this document is quite a bit older than the eighth century. As I’ve noted, there were a tremendous number of legendary documents and forgeries cropping up around first of all, the person of Peter in the second century, and later around the office of Bishops of Rome after the time of Constantine. Among these was a document known as The Acts of Sylvester. Shotwell and Loomis briefly describe this document, “originating, as they probably do, before the period of our study is over, and making bold capital for the Roman See out of the renown of the Great Constantine by ascribing that emperor’s bodily healing and religious conversion of the agency of the Roman bishop Sylvester. Ignored at first by every reputable historian, this fable made its way, gathering volume as it went, re-enforced eventually by a forged Donation, until it had imposed upon all Europe the conception of Silvester as the potent influence behind Constantine’s most striking measures and of Constantine himself as the dutiful servant of the See of Peter.”
This “Acts of Sylvester,” they classified, as among “the apocryphal achievements of the early bishops, the spurious acts, miracles and decrees attributed to them, invented apparently, as the apocryphal Acts of Peter were invented, to enhance the popular reverence for the supposititious doer.”
As Wilson had noted about the Donation, the exact circumstances of the creation of this legend is unknown. But not only was it a “complete lie,” but as Reymond noted, it was one of the with many inventions, fictions, and forgeries, that not only became dogma, but which then was “foisted upon the world” in the service of the insatiable Roman quest for power.
Sounds like deception to me.